Docosanol (I) is a drug used for topical treatment for recurrent herpes simplex labialis episodes (cold sores or fever blisters). A saturated 22-carbon aliphatic alcohol, Docosanol (I) exhibits antiviral activity against many lipid enveloped viruses including herpes simplex virus (HSV). It is marketed in the US as 10% topical cream.
The synthesis of Docosanol (I) has been reported in few patents and non-patent literature, the contents of which are hereby incorporated as reference in their entirety.
U.S. Pat. No. 7,718,834 describes the process of preparing primary long-chain alcohols or mixtures thereof by a growth reaction of ethylene on aluminum compounds. Similarly, U.S. Pat. No. 7,141,611 describes a process of obtaining the alcohol mixture by extracting from natural products, using organic solvents with or without saponification.
One of the main disadvantage of the prior art literature reported so far is the use of raw materials from natural sources which provide mixture of fatty acids which are difficult to separate which in turn results in low yield of the desired component. Also, use of highly specific reagents restricts the use of these processes in large scale. Hence, the present inventors have reported a novel synthetic process and purification technique for the preparation of pure Docosanol (I) which is cost effective, simple and employs less expensive chemicals, which makes it more feasible at industrial scale.
The present inventors also found novel crystalline forms of Docosanol (I).